Contexts as moderators of observed interactions: a study of Costa Rican mothers and infants from differing socioeconomic backgrounds.

20 first-born infants from low socioeconomic status (SES) families and 20 first-born infants from middle SES families in Costa Rica were observed for 12 hours when they were 14 weeks old. The goals of this study were the following: 1) to study the impact of length of observation and context on the authors measures of interactional engagement; 2) to compare the interactional experiences of the infants in the two groups in various functional (e.g. feeding, object play) and social (e.g. with mother, with mother and others) contexts. Attuned and disharmonious interactions, as well as the frequency of positive affect, soothing, and vocalization, varied considerably across the functional contexts. In addition, disharmonious interactions increased and interactional engagement decreased when mothers and infants were joined by others. Highly unstable measures of individual differences were obtained when observations were limited to 45-minute blocks, but stability increased considerably as the duration of the observations expanded. The groups did not differ with respect to amounts of time spent in various functional and social contexts, in attuned or disharmonious states, or in high levels of interactional engagement. Within some of the functional contexts, however, significant group differences in levels of attuned interactions, infant vocalization, and maternal response vocalization were found. Overall, functional and social contexts clearly moderated interactional experiences. SES effects on verbal and other interactional measures were limited to some contexts and may thus represent the infants' overall experiences quite poorly. Consequently, comparisons based on a single context may be inadequate for studies of subjects from differing socioeconomic backgrounds.